Intelligence transmission system



Feb. 14, 1939. v, K. zwoRYKlN INTELLIGENCE TRANSMISSION SYSTEM FiledJan. 4, 1957 3 Sheets-Sheet l BY 5 u 4 ATTORNEY lll" Feb. 14, 1939.

v. K. zwoRYKlN 2,146,876

INTELLIGENCE TRANSMISSION SYSTEM Filed Jan, 4, 1937 3 Sheets-Sheet 2 '7Lo l ./I y

INVENTOR I VLADIMIR K.ZWORYKIN I IIJ UME ATTORNEY Feb. 14, 1939.

V. KA ZWORYKIN INTELLIGENCE TRANSMISSION SYSTEM 5 Sheets-Sheet 3 FiledJan. 4, 1937 SAM/7007.1

INPUT v Fay. 8a

`/l/lU/l/ 70 Mom/mm@ 0F MMM/fm2 SOI/RCE INVENTOR vLAmMlR KJWORYKIN vATTRNEY Patented Feb. 14, 1939 UNITED STATES.

2,146,876 m'rELLIGENcE TnANsMrssioN sYs'rEM Vladimir K. Zworykin,Philadelphia, Pa., assignor to Radio Corporation of America, acorporation of Delaware Application January 4, 1937, Serial No. l119,026

21 Claims.

The present invention relates to television systems and is particularlydirected to television systems wherein the pictorial action istransmitted with all accompanying sound indications which occur with andare coordinated with the pictorial representation.

This invention is a continuation in part of my copending applicationSerial No. 665,098, flied April 8, 1933, and entitled Intelligencetransmission systems".

In sound motion picture work it is customary to produce a lm record onwhich there are a series of pictorial representations intermittentlyproduced with which, and usually adjacent these pictorialrepresentations, there is also a continuous record of the sound whichaccompanies the pictorial action. Such a sound record may be of varioustypes such, for example, as the variable density or the variable widthtype recording, or

' the sound action may appear upon a separate record from which itv ismechanically or electrically reproduced. In such a case, however, thereproduction must be accurately coordinated with the lm in reproductionso that there is no observable lapse of time between the observation ofthe action and the hearing of the related sound.

Television, it has been found, is improved to a considerable degreewhere the observation of the reconstructed image of the object at thepoint of transmission is accompanied by a series of sound signals whichserve to make the visual action more realistic.

It is with a view to producing a television system havingcharacteristics of this general nature that the present invention isdeveloped.

In the prior art, so far as I am aware, frequent endeavors have beenmade to transmit simultaneously both image and sound signals, as well assignals to synchronize both the image and the sound, but these previousendeavors usually involved transmitting the picture signals upon onecarrier frequency and transmitting the sound signals upon anothercarrier frequency which is separated from the picture signal ortelevision carrier by a predetermined separation, usually at least equalto the frequency separation corresponding to the highest modulationfrequency of the television transmitter. -According to another systempreviously suggested in the prior art, as shown for example by`Goldsmith et al. Patent No. 1,770,205 assigned to Radio Corporation ofAmerica, it has been suggested to transmit the television signals asmodulations of one carrier frequency and then` to modulate a secondcarrier 55 frequency by the sound signals and then, in turn, l

(ci. 17e-5.6)

to modulate the television carrier also by the sound modulated carrierfrequency.

The present invention attempts to improve upon vthese systems of theprior art and has as its principal aim and object that of transmitting 5both the television and sound signals, as well as. any desiredsynchronizing signals, upon the same carrier frequency so as to avoidthereby the necessity of generating independent carrier frequencies andproviding more than a single modu- 10 lator for modulating the generatedcarrier by both the television and the sound signals. In

this system sight and sound transmission is so interlocked that thepresence of one type of signal substantially assures the presence of theother. 15

In television transmission the frequency band required to transmit asatisfactory image representation is a function of the number ofcomplete image transmission, that is, thevscanning frequency, as well asa function of the number of 20 image points into which each image isassumed to be divided for the purpose of transmission. In transmitting24 complete image representations per second, for example, which areeach assumed to be divided for transmission into 250 elemental strips,each composed of 300 individual elemental areas, for example, it can beseen that the frequency band required approaches 1 megacycle.

When recourse is had to the cathode ray tube as a transmitting and/orreceiving instrumentality it is customary to use the cathode raygenerated within the tube to scan an object or to reproduce an image ofthe scanned object for approximately 1% of the time available. Thispractice originates because of the fact that the cathode ray to scan orto reproduce a picture traverses -either the photo sensitive element ofthe scanning tube 0r the uorescentscreen of the receiving-tube at arelatively slow speed in one direction but at a rapid speed in the otherdirection lso vthat the o scanning or analyzing appears to occur alwaysY inpone direction. The 116 of the time lost from scanning orreproduction occurs during a reversal of the cathode ray beam from amaximum deection toa position of starting or minimum deflection.

This reversal of the cathode ray has commonly been termed the returnline period and in this period it is customary to transmit asynchronizing signal-by which the synchronizing signal generators oroscillators at both the transmitter and receiver may be locked in stepso as to cause the cathode ray beam at both the transmitter and thereceiver to operate synchronously. Where the frequency band required isof the order of 54 1 megacycle it is seen that there is, in fact, a lossof substantially 100,000 cycles of intelligence transmission occasionedby the reversal of the cathode ray beam and this full loss cannot becompensated by the inclusion of the synchronous signal within the timeperiod of reversal oi.' the cathode ray, since the synchronizing signalusually requires only substantially V2 oi.' the reversal period fortransmission. Hence, it is in this time period which heretofore has beenlost, so far as intelligence communication is concerned, that it isproposed to transmit the sound signals which accompany the pictureaction for each assumed elemental strip of the subject which isreconstructed by the cathode ray at the receiver in its slow transversalfrom one edge portion to the opposite edge portion of the uorescentviewingscreen.

Therefore, it is an object of the present invention to transmit acombined television and sound indication upon a single carrier modulatedsequentially by television and sound signals and, where desirable, alsomodulated in the time space between the occurrence of the televisionsignals and the sound signals by such synchronizing as may be necessaryto frame and synchronize properly the reproduced images.

It is a further object of the present invention to provide ways andmeans by which sound and television signals may be transmitted upon asingle carrier frequency without causingany interfering action one withthe other.

It is still a further object of the invention to provide a system fortransmitting sound signals related to television image'signals in whichthe sound signals occurring within a relatively long time period may betransmitted within a relatively short time' period and then caused tobecome audible at the points oi.' reception during the same relativelylong time period as they occurred at the point of transmission.

It is a further object of this invention to provide ways and means forcondensing' the sound occurring within the time required to scan asingle elemental strip of a subject 4of whichthe image is desired andthen to transmit in .the interval between the periods of transmissionoi.' signals representative of the successive elemental strips of thesubject this condensed sound record which at the points of reception isagain expanded and caused to produce audible signals reproduciblesimultaneously with the production of the next succeeding series oflight values corresponding to the next succeeding elemental strip of thesubject oi' which the image is being produced.

It is a further object of this invention to provide a system wherein acondensed sound record may be produced as a series of electrostaticcharges occurring within a relatively long time period and thentransmitted in inverse order during a relatively short time period,after which the transmitted sound signals produce at lall pointsofreception a similar electrostatic record in inverse order to that of thesound production and in condensed form from which it is then expanded soas to become audible during a time period corresponding to the timeperiod required ior the production ci the original electrostatic recordfrom which the sound signals are transmitted.

A further object of the invention is to provide a television systemwherein appropriate control production of and the transmission of theelectrostatic sound indications produced by voice or equivalentmodulation.

Further objects and advantages of the invention are to provide a systemfor transmitting a combined television and sound record which isconsiderably simplied from the systems at present in use and in which nointerference between sound and picture signals can arise; to provide asystem which is simple in its construction and arrangement of parts; toprovide a system which can be compactly arranged in a receivinginstrumentality so as to adapt more easily the system to commercial use;and to provide a system for receiving television and sound signals whichcan be distributed and sold at retail at a minimum purchase price.

Still other and further objects of the invention will be pointed out inconnection with the description of apreferred embodiment of thisinvention, while many other objects will naturally suggest themselves tothose skilled in the art to which the invention is directed by readingthe following speciication and claims in connection with theaccompanying drawings wherein:

Fig. 1 is agraphical representation of the curve plotting the amplitudef the cathode ray deflection with respect to time and represents asingle traversal of the cathode ray for example from right to left andleft to right;

Fig. 2'illustrates in diagrammatic form a system for storing soundsignals as electrostatic charger which later may be utilized to transmitan audible record;

Fig. 3 illustrates in conventional manner a suitable system fortransmitting combined television and sound signals;

Fig, 4 illustrates a receiver system for cooperative use with thetransmitter shown by Fig. l;

Fig. 5 illustrates in portion (a) the scanning and return line path ofseveral traversals of either viewing screen of the receiver or lightsen- 'sitive element of the transmitter, `and portion (b) indicatesconventionally the signals representative of both picture synchronizingand sound for onesingle scanning line;

Fig. 6 diagrammatically represents the tube used to store as theelectrostatic charges a series of sound signals' occurring within thescanning period of a single line of a subject of which the imageis'being produced, and in this iigure the portion (a) represents a topportion looking down upon the tube shown, for example, by Fig. 2, andportion (b) indicates a lower view of the storing elements of the tubeof Fig. 2, for example;

4 Fig. 7 diagrammatically illustrates a wave shaping circuit forproducing saw-tooth current for use in the deecting circuits;

Figs. 8a, 8b andr 8c illustrate graphically voltage waves and a currentwave as an aid to explaining the operation of the circuit'shown in Fig.7, and

Fig. 9 shows in greater detail one of the embodiments which the systemi'or storing sound illustrated in Fig. 2 may take.

To make' reference now to the drawings forming a part of thisspecication and disclosure, it can be seen, from the showing of Fig.1,'that the time required to produce one single picture line or, inother words the time required to scan one single elemental strip intothe subject of which the image is desired isi-assumed to be divided. canfor purposes of illustration be regarded as, unity. This 'time periodmay then be assumed to be divided into two distinct portions desi--nated as I and II. During the time period designated as I the curve ofamplitude against time is seen to rise from substantially a zero valueto a maximum, and during the time period II is seen to return again to azero value. For purposes of further explanationv the time period I hasbeen further identified as A and it is during this period that thecathode ray which may be assumed'to sweep from the left edge of eitherthe light sensitive element or plate of the transmitter or the uorescentscreen of the receiver. 'Ihis motion or deflection of the cathode raypencil or beam occurs at a relatively slow rate. However, as soon as thecathode ray beam reaches its maximum amplitude of swing in one directionit must be returned rapidly to the starting position so as to beprepared to .traverse again the photo-sensitive plate of the transmitteror the uorescent screen of the receiver and it is this portion of theswing or deilection motion of the cathode ray'that is identied as theportion II of the curve of Fig. 1. During the period II nov pictorialintelligence can be transmitted and therefore, this time period, whichamounts substantially'to 110 of the total time period available, is lostso far as pictorial intelligence trans- 'mission is concerned. It is,therefore, during this time period that it is proposed, according to thepresent invention, to transmit both the synchronizing and the soundsignals. The return line period designated as II is, therefore, assumedto be divided into three'distinct periods or portions B, C, D. Duringthe periods B and D synchronizing signals serving to synchronize thecathode ray beams at the transmitter and all receiving points may betransmitted, and during the portion C, which otherwise is not utilizedfor transmission, it is proposed to transmit all of the sound whichoccurred during the period A which represents the period pictorialintelligence transmission.

If it is assumed that the pictorial subject of which the image isdesired is divided into 250 elemental strips, for example, and the rateat which complete pictorial representations are transmitted is 24, thenit is seen that the total time required to move the cathode ray from aposition of zero amplitude to a maximum and back to a zero amplitude isof the order of 143000 of a second and that the time period required tomove the cathode ray from a position oi maximum to a minimum amplitudeis of the order of 1450000 of a second. Therefore, it is during this$60000 of a second time period which otherwise cannot be utilized exceptto transmit the synchronizing signal that the sound signals occurringwithin the period designated as A or during 1% of each $0000 of a secondtime period should be transmitted.

If reference is now made to the showing in Fig. 2 sound signals whichmay be producible either by optically analyzing the sound record portionof a motion picture iilm record through appropriate light translatingelements or which may originate through the mechanical or Aelectricalpickups from a phonograph type of record or which may be spoken, forexample by the subject being televised, are caused to iniiuence andmodulate a microphone I which is connected with an appropriate amplier3. 'I'he output signals from the amplifier 3 are then caused to controland modulate a cathode ray 5 generated within the cathode ray tube I soas to control in amanner generally similar to the system for control ofthe cathode ray shown and described by patent to Nicolson No. 1,470,696assigned to Western Electric Company, so as to permit the production ofan electrostatic sound record in a manner to be hereinafter described."i

The cathode ray tube 'I is provided with the usual electron emittingcathode 9, a grid control element II and an anode I3. Instead of ailuorescent endwall, as shown by the above mentioned Nicolson patent,the cathode ray tube 'I is provided atits end portion opposite theelectron source with a series o! storage or' condenser elements,generally designated at I5, which will be described more fully as totheir construction in connection with the description oi. Fig. y6. Ingeneral it may be stated that the condenser elements I5 are formed froma conducting end plate Il adjacent to which is a layer of mica or othersuitable insulating material I9 to the under side of which is a secondconducting plate, generally designated at ZI. A carbonized material 23coats independent sections of the plate 2l so as to form from themetallic layer 2| a member which has sections of different electricalproperties s0 that there is a variance in the emission of secondaryelectrons over diierent portions of the plate or electrode area.

If now the cathode ray pencil 5 -generated within the cathode ray tubeis modulated as suggested by the above named Nicolson patent, by thesignals appearing in the output of the ampliiler 3 which are connectedto the grid and cathode elements II and 9 of the tube I by way ofconductors 25 and 21, the modulated cathode ray pencil will be capableof producing diierent electrostatic charges upon the individualcondenser elements including the plates I 'l and 2| separated by theinsulating layer I9. These varying charges represent the varyingamplitude sound modulation frequencies appearing in the output circuitof amplier 3 during the scanning period A. As these varying charges arebeing produced the cathode ray pencil 5 is, according to the showing ofFig. 2, moved from right to left by means of varying voltages appliedfrom a source (not shown here but illustrated' in Fig. 3) in accordancewith the amplitude-time curve of Fig. 1 to the defiecting plates 29, 29'by way of conductors 3l and 38 of which thelatter is grounded at 35. orconnected to the cathode element or the tube which is grounded at 35.

Suitable anode potential to cause the cathode ray to be projected fromthe cathode 9 to the condensers I5 is supplied between the anode elementI3 and the cathode 9 by wayV of a battery or other suitable source 35,which in a commercial installation is usually the well known socketpower unit serving to Supply all operating voltages from analternating-current source.

Let it now be assumedthat the cathode ray pencil 5 is moved from itspoint of greatest deection tothe left of the position shown in Fig. 2over to its maximum deflection at the right of Fig. 2, or that voltageshave been supplied to the delecting plates 29, 29' as shown by-theportion o, a. of the curve I of the curve of` Fig. 1 so that the cathoderay is just ready to'move rapidly from right to left, or in other wordsfrom'maximum to minimum deflection, accordingto the portion of .l curveof Fig. 1 designated as-II. Y

the grid cathode circuit ot the cathode ray tube 1. The cathode raypencil 5 is consequently.

free from intensity variations and is, therefore. at normal" intensityduring the period when it sweeps from the right hand portion of thecondensers I5 of Fig. 2 over to the left hand portion, and secondly, thecharges which have been stored in the various individual capacityelements forming the condenser element l5 are discharged. These chargesare then applied to the input circuit -of ampliiier 31. Amplifier 31,during the period when sound modulation frequencies are supplied to thegrid-cathode circuit of the cathode ray tube 1 is biased to cut-off bythe same variable biasing source now serving to bias the amplier 3 to'cut-oil'. Therefore, during the period of rapid traversal of the cathoderay across the several condenser elementsy I5 the sound signals whichhad been converted into electrostatic charges appear in the outputcircuit of the amplifier 31 which connects to the modulator of thetransmitter (not shown ln this figure) in inverse order to that of theirproduction. Thus, the sound signals are amplified and transmitted withina time period substantially no greater than 1,6 of the time periodduring which the sounds were produced.

As soon as cathode ray pencil 5 is returned to the plate at the extremeleft hand edge portion of the tube 1, looking at Fig. 2, thevariablebias source serves tobias the amplitler 31 to cut-oi! but no longeraiects'amplifler 3. In this manner, amplifier 3 is again able to supplysound modulated signals to the grid electrode of the cathode ray tubeand thus to charge again the various capacity elements to diilerentdegrees for the purpose of producing an electrostatic record of thesound originating at the microphone i within the time periodcorresponding to the slow traversal of the cathode ray from left toright, after which the same sequnce of events hereinabove mentioned isrepeated again and again until the entire picture and sound transmissionis complete.

Reference may now be made to the showing in Fig. 3 of the drawingswhichv illustrates, partly in schematic form, a complete televisiontransmitting system provided with means for-transmitting related soundsignals. In this arrangement, for convenience of illustration, it hasbeen assumed that a motion picture film 4I is the subject of which theimage is desired, although, of course, it is recognized that any type ofsubject or an indoor or outdoor scene may be substituted for the filmwithout departing from the spirit and scope of this invention. If a filmsubject 4l is used as the subject from which visual intelligence is tobe transmitted, this subject is moved, preferably intermittently,relative to the scanning device, such as the cathode ray tube 43, in thegeneral direction shown by the arrow. Each frame portion of the filmsubject 4I is illuminated from an intense light source 45, such as anarc or other suitable type, which directs the issuing light therefromthrough an appropriate optical system 41 through to the film. In.

accordance with the varying transparency of the lm light ofproportionately controlled intensity is directed by means of a secondoptical system 48, which is'usually formed from a plurality ofindividual lens elements, so as to be focused upon the light sensitiveelectrode or plate 5i contained within the scanning tube 43. Thescanning tube in the form herein illustrated may be of the samegeneralconstruction as was andere shown and described in my co-pendingapplication Serial No. 574,772 iiled November 13,1931 and assigned toRadio Corporation of America (Docket #2000) wherein there is disclosedthe screen structure 4l in the form of an insulating sheet upon one sideof `which is a thin conducting nlm 50 and upon the other side of whichis a uniformly distributed series of individual photosensitive elements5|. These photosensitive elements may, where desired, be formed in themanner disclosed by Sanford F. llissigv in application Serial No.594,779 filed February 24, 1932 (Docket RCA Victor 2059) and assigned toRadio Corporation of America.

Within the scanning tube 43 there is generated by means of theco-operatlve action oi' a cathode 53 and an anode 55 a cathode raypencil 51 which is adapted, when suitably deiiected in a vertical planeby the electrostatic deiiecting plates 50 and 59' and in a horizontalpath by the electromagnetic deflecting coils Bi and 5I', to sweep theentire area ofthe light sensitive plate 5I. Whenever light from the nlmis projected upon elemental areas or sections of the light sensitiveelectrode or plate 5I the individual elements thereof emit electrons andtake on positive charges corresponding in value to the light intensitiesto which they are subjected. Thus. an electrical image of the subject orobject is developed over the surface of the screen structure.

In orderto utilize the electrical image to reproduce at a receivingstation the electrostatic charges referred to are neutralized ordischarged successively by causing the cathode ray pencil 51, to scanthe photosensitive surface 5I under the influence oi the electrostaticdeiiecting field produced between the deflecting plates 59 and 55' andby the electromagnetic deiiecting eld produced by the coils 8l and 8l'.

For the purpose of removing the electrons of the ray pencil 51 which arenot required to neutralize the respective positive charges accumulatedby the individual photosensitive elements I5, as well as the electronsemitted by these elements in taking on these charges, a suitablecollector or anode 63, in the form of a screen, is supported in theproximity to the photosensitive surface of the screen structure and ismaintained at a positive voltage through conductor 13 connecting to asuitable source 11, leading to ground at 61', as shown.

The successive discharges oi' the positive charges upon the individuallements 5|, as explained, causes corresponding current impulses orpicture signals to4 be developed across the resistor 83 in the grid orinput circuit of a suitable picture signal ampliiier 85, for whichpurpose the platinum film 50 is connected to this-circuit by a conductor69 and one of the wire supports 52 carrying the screen structure 40.

The synchronizing signals for deflecting the cathode ray pencil 51 in ahorizontal direction are generated in a synchronizing signal generator11 which generates a wave of the saw-tooth type substantially as shownby Fig. 1. These signals are supplied to the horizontal deflecting coils6l and 6I' by way of the conductors 19 and 19' and the shaping circuit|19. Similarly, the verandere higher frequencies, however, dicultyarises in that the deflecting electrodes constitute a con denser and theupper harmonics present in a sawtooth wave are of such high frequencythat the impedance of the condenser represented by the deflecting plates|51 virtualy short circuit these components and destroy the linearity ofthe sweep voltage with respect to time.

Accordingly, electromagnetic coils through whicha suitable voltage wavemay be applied is desirable. It should be understood, of course, that toapply a saw-tooth voltage wave to such coils would also result indistortion since the impedance of the coils at highfrequenciesdiscriminatesagainst high frequency current components. To overcome thisdifficulty, the saw-tooth wave is passed through a wave shaping circuit119 which predistorts the voltage wave so that when the distortedvoltage wave is applied to the deecting coils a truesaw-tooth currentwave results. The saw-tooth current wave, therefore, produces anelectromagnetic field which builds uplinearly with time. Such a waveshaping clrcuit is shown in Fig. 7 and is in form of the same type ofcircuit described in considerable detail in an application numbered544,959 by Arthur W. Vance, entitled Intelligence transmission systems,which application was iiled June 17, 1931 and upon which application aBritish Patent No. 395,499 has been issued on July 30, 1933.

Referring now to Fig. 7, a saw-tooth wave as shown in Fig. 8a is appliedto the input of the wave shaping circuit 119 across the resistor 205.This wave is amplified by the triode 20! and across the plate circuit ofthis tube there appears avoltage wave shown in Fig. 8b. The inductance201 may be of the order of 100 henrys or more, so that it actssubstantially as open circuit for the alternating current components butpermits the D. C. plate current to be maintained constant. Connected inparallel with the inductance 201 is serially connected resistor 209 andcondenser 2| l. The grid of the tube 203 is connected to the seriallyconnected resistor and by suitable adjustment of the movable tap on theresistor 209 the proper wave shown in Fig. 8b can be obtained. Thisvoltage wave isv linearly amplied by the tube 203 and the lconstance ofthe choke 213 and the condenser 2| 5 are so-chosen as to present avoltage wave across the terminals 2I1 which is substantiallyproportional to the voltage wave shown in Fig. 8b. This voltage waveapplied to deflecting coils, for example, |61 and |63, then produces asaw-tooth current wave as illustrated in Fig. 8c. From the terminals 211leads are likewise brought down to the amplifier bias source |29 for thereasons as will be pointed out more fully below. It will be understoodthat in accordance with the teachings of the Vance application andpatent, the condenser 2H may have substituted for it an inductance, thechoice oeng merely one of convenience.

The frequency of the horizontal synchronizing signals is equal to thenumber of elemental strips into which each image representation isassumed to be divided for purposes of analysis multiplied by the numberof complete image representations per second.

As varying voltage drops are produced across the resistor 65 so' as torepresent the varying light values reaching the light sensitive element5i various potentials on the control grid of the ampliiier tube 85produce proportionate output currents which are then transferred to asecond amplifier 81, usually a multistage amplifier, whose output isconnected. to the modulator 89. The oscillator 9i serves to generate thecarrier frequency and connects with the modulator 59 which is in turnconnected with the transmitter amplier 93 from which the energy outputis -transmitted to various points of reception either by way of a radiotransmission linlr from the antenna 95 or by way of a wire line'transmission link, where it is desired to send the television signalsover a Wire line.

As was explained above in connection with Fig. 2, sound signals may besupplied directly to the microphone i or may be translated from the lmrecord 4| which is being explored for image' transmission purposes. Thesound signals there l converted by the microphone or photocell intoelectrical signals are then supplied to the sound signal amplifier 3. Aswas also explained. in connection with Fig. 2, there sound signalsappear across the grid cathode circuit of the vcathode ray tube 1 andserve to modulate the generated cathode ray pencil 5 within this tube.The

output signals which are produced from the electrostatic charges formedin the condenser elements I5 are Asupplied to the amplier 31. YTo eachof the ampliers 3 and 31 there is connected an amplifier biasing source91 controlled from the synchronizing signal generator 11 forhorizontaldeilection of the cathode ray pencil which serves alternatelyto bias ampliers 3 and 31 to cut-ofi. The amplier biasing source 91 maybe, for example, the device shown in co-pending application of H.Branson, Serial No. 644,417,

led November 26, 1932, and entitled Ainpli-r ers on the basis of whichapplication British Patent No. 415,619 was accepted August 30, 1934, orthe circuit shown and described in the Branson British Patent No.834,891, accepted September 11, 1935, or the Shore Patent No. 2,005,111issued June 18, 1935, and entitled Ampliers.

It is desirable to maintain cut-0H bias on amplifier 31 for a relativelylong time period, or in other words for a time period represented by thetime period I of Fig. 1, and during this same Atime period I theamplifier 3 should be maintained in an operative state, whereas for thetime period II (see Fig. l) the amplier 3 for sound signals should berendered inoperative, or in other words biased to cut-o, whereasamplifier 31 should be operative. To produce this result the biasingaction produced from the bias source 91 and eiective upon amplifiers 3and.31 changes in accordance with the rate or frequency of thesynchronizing signals generated so that the ampliers 3 and 31 arerendered alternately operative and inoperative for time periodscorresponding to the above enumerated conditions.

vThe operation of the bias ampliiier 91 will now be described in detail.Referring nowto Fig. 9, there has been shown in detail the conventionalampliers for the microphone and for the sound channels 3 and 31respectively together with the bias amplier 91 which, for purposes ofillustration, is shown as the type of amplifier disclosed in the ShorePatent No. 2,005,111 referred to above. A voltage wave havingthe shapeshown in Fig. 8b is derived from the .output of the wave shaping circuit|19 and fed to the input terminals 2|3. The tube 22| is normally biasedt0 cut off by the battery 223 so that there appears Vacross the plateresistance 225 no voltage drop. The plate resistor 225 is also made partof thecathode grid circuit of tube 231 of the amplifier 31 and undervsuch conditions, voltages applied to the terminals 239 are linearlyamplified through the tubes 231 and 233, the output of which is fed tothe modulator of the transmitter. The tube 23| has its grid connected tothe plate resistor 225 and is biased by the battery 233 to anappropriate value-so that current normally flows through the plate.resistor 235, under the conditions of tube 22| being biased to cut-off.The voltage drop across the resistor 235 is fed to the tube 221, in itscathode grid circuit, and'in such polarity as to bias the tube 221 tocut-oil and of such magnitude that any signal voltage applied from themicrophone is insufficient to actuate the amplifier. A condenser 240 isconnected from the plate resistor 235 to the grid of the tube 22| inaccordance with the teachings of the Shore patent, referred to above.When the voltage wave of the form shown in Fig. 8b is applied to theterminals 2|9 current begins to flow in the plate circuit 225 of thetube 22|, producing a voltage drop, which is then amplified by the tube23| and a portion of the energy fed back as positive regeneration to theinput circuit of the tube 22|, which process repeats until saturationcurrent flows in the tube 22|, 'under which conditions, tube 23| has somuch negative voltage applied between its .grid and cathode by virtue ofthe voltage drop through the resistor 225 taking place, due to currentflowing through tube 22|, that the tube is cut of! so that no platecurrent ows through the resistor 235. Under these conditions the voltagedrop across the resistor 225 is now sufficient to cut 0E the tube 231 sothat' there is no longer any voltage fed to the modulator of thetransmitter. At the same time, since there'is no plate current flowingthrough the resistor 235, tube 221 is biased linearly by the battery 228and signal voltage obtained from the microphone is linearly amplifiedand has its output passed on to the elements I I and 9 of tube 1. Whenthe linearly increasing portion of the wave shown in Fig. 8b ceases. andthe abrupt collapse takes place, the operation of tubes 22| and 23| arereversed, since the tube 22| goes back to its cut oi condition andthetube 23| begins to draw current. Under these conditions then, theamplifier 3 is rendered inoperative, and the amplifier 31 is renderedoperative. It will thus be observed that the microphone amplier isoperative during a relatively long period and the amplier 31 .operativeonly during a short period.

The horizontal synchronizing signal generator 11 which serves to movethe cathode ray pencil 51 transversely in the scanning tube 43 is alsoconnected by yway of conductors 3| to the deecting plates 29 and 29' ofthe tube 1 so as to cause the generated cathode ray pencil 5 to moveback and forth across the tube in an appropriate manner.

The sound signal amplier 31 connects with the modulator 39 so that the.amplified sound signals serve also to modulate in modulator 39 thegenerated carrier frequency as generated by the oscillator 9|. The.sound modulated carrier frequency signals are likewise suitablyamplified in the transmitter amplifier 93 andl transmitted from theantenna 35 or by way of a suitable wire line connection to all receivingpoints.

If the synchronizing signals are generated in the generators 11 and 3|are supplied to the modulator 33 in such manner as to be 180 out ofphase with the picture 'signals transmitted to the modulator 39 by theamplifier 31 and the sound signals transmitted to "the modulator 39 bythe amplifier 31 vthe synchronizing signals will correspondsubstantially to black signals, as has already been disclosed in theco-pending applicationof R. D. Kell, Serial No. 565,953 filed September30, 1931 and assigned to Radio Corporation of' America (Docket #1607). y

In this manner the signals which are transmitted from the transmitteramplifier 93 follows the following sequence:rst, picture modulatedsignals which occur during a relatively long period of time designatedas time period A; second, synchronizing signals occurring during arelatively short period of time designated as time period B; third,sound signals .which also occur during a relatively short perioddesignated Vby the time period C; and then fourth. where suggested byFig. 4. Where the transmission is by radio the signals may be receivedupon the antenna system 91 and suitably amplified and.

detected in a receiver detector amplifier 99 to which the output of thelocal oscillator |0| is sup-l plied. The resulting intermediatefrequencies are then amplified in the intermediate frequency amplifier|03 from which the sound signals may be detected by the detector |05 andfrom which the picture and synchronizing signals may be detected in thedetector |01.

The sound signals detected in detector |05 are then suitably amplied bythe amplifier |09and are supplied to the cathode ray tube III across thegrid and cathode elements I I3 and I I 5 respectively so that .thecathode ray pencil I|1 passing beyond the anode I I9 is controlled inintensity in proportion to the received sound signals. This intensitycontrolled cathode ray pencil |I1, which is synchronized in its motionwith the cathode ray pencil 5 of the tube 1, then charges a series ofcapacity elements generally designated I2| during its rapid sweep ordeection path from right to left to degrees proportionate ,to thereceived sound transmitted within the time period C shown by Fig. 1. Inthis manner an electrostatic record of the received sound signals isproduced upon the capacity elements I2I and later, as will herein bepointed out, this electrostatic sound record may be utilized in inverseorder to that of its production to cause at each receiving point anaudible record of the sound which influenced the microphone or otherform of pick-up device I f at the point of transmission.

'This is made possible by causing the cathode ray pencil |I1 to be sweptback and forth from right to left and left to right over the capacityelements I2I by supplying varying voltages to the deflecting plates |23and |23' from the source of horizontal synchronizing signals asgenerated in the synchronizing signal generator |25. 'I'hese controllingvoltages are conveyed to the deflecting plates of the tube I I by way ofconductors |21 and |21' so that the cathode ray pencil |I1 in the tubeIl is synchronized properly with' the cathode ray pencil |49 of theviewing tube to be hereinafter described. y

As was pointed out in connection with the descriptin of Figs. 2 and 3,the sound signal ampli- -er was alternately biased to cut-ofi' andrennizing signal generator |25 so that during the time period of rapidmotion of the cathode ray pencil 1| 1 within the tubey il the inputsound signal amplifier |99 may be rendered operative and during the slowvmotion period, corresponding to the time period I of Fig. 1, theamplier |09 is biased to cut-oil or renderedinoperative. It will benoticed that the time period of operation of the i-nput sound signalamplifier |09 thus corresponds to the time period of operation ofthesound output signal amplifier 31 of Fig. 3 and that the time period ofinoperativeness of the amplifier |09 corresponds to the period ofinoperativeness of the amplier 3 of Figs. 2 and 3.

As the cathode ray pencil H1 sweeps across the capacity elements |2| ofthe tube from right to left the amplier |99 is operative. In this waythe cathode ray pencil i1 is modulated by the signals received and thecapacity elements are charged to different degrees'y proportionate tothe sound to be reproduced. During the period when the cathode raypencilH1 is reversed in direction so that it sweeps slowly across the capacityelements |2| of the tube the amplier |99 is inoperative from theamplifier bias source |29, and thus no sound signals can be suppliedacross the grid cathode circuit ||3 and of the tube which means that thecathode ray pencil I I'i is not variably controlled as to intensity butis, in other words, at full intensity. At this time period the fullintensity uncontrolled intensity cathode ray pencil H1, which is nowassumed to be moving from left to right within the tube iii will serveto discharge the sound signal charges stored on the capacity elements12|. These discharge signals are than supplied to the sound signalamplifier |33 which is now rendered operative by the ampliler'biasingsource |29 connected thereto by Way of conductors |35 and |35. 'Iheamplied sound signals which appear in the output circuit of theamplifier |33 are now rendered audible by the sound reproducer |31. Thisperiod of audibility since it occurs during the time period designatedby I in Fig. 1 corresponds, to the period of operativeness of thecathode ray pencil within the picture reproducing tube, to behereinafter described. The relatively long time period of operativenessof the sound reproducer |31 coordinates the reproduced sound with thereproduced picture and, at.the same time, the manner of reproductionproduces a reversal and expansion intime of the received sound signalsso that the sound instead of being heard during the short time period atwhich it is recorded electrostatically within the tube becomes audibleduring a relatively long time period and in an order, of course,corresponding to the order of occurrence or pick-up at the microphone ofFigs. 2 and 3. So arranged, it can be seen that the sound as it becomesaudible is delayed by a. time period corresponding to that of scanning asingle elemental strip of the picture, or in other words, if the soundoccurred durl ing the period I oi the scanning cycle. designated in Fig.1 and was transmitted during the time period II of the same scanningcycle, it will become audible during a similar period I of the followingscanning cycle. This delay will be unobserved because the human earisnot sufliciently sensitive to detect such a small time delay in thesound reproduction with respect toL the picture action. In fact, it hasbeen noted that the human ear is usually substantially insensitive totime delays of as,A much as M0 of a second. In the present system thetime delay of the reproduced v sound'accordlng to the above assumedconditions may occur with a delay of as little as 115000 of a secondwith a maximum delay period of one scanning cycle plus the $13000 of asecond time period. Y

To reproduce now the picture portion of the transmitted intelligence,the picture signals which have been detected in the detector |91 aftersuitable amplification in the intermediate frequency amplier E93 areagain amplified to a still further degree in the picture andsynchronizing signal amplifier IM. So amplified these signals Y areimpressed across the control circuit of the voltage relative to thecathode is supplied by way of a battery |53 or directly from the socketpower unit. In order to provide for sharply focusing the cathode raypencil |99 upon the fluorescent end Wall |55 of the tube M3, I haveherein shown a system wherebythe beam may be focused*electrostaticallyas has already been disclosed in my copending application Serial No.407,- 652, filed November 16, 1929, assigned to Westinghouse Electric @aMfg. Co., (Docket 14,718) and also which has been disclosed by pendingapplications of Pierre E. L. Chevallier, Serial Nos. 489,- 957 and630,397 iiled respectively on October 20, 1930 and August 25, 1932,assigned to Radio Corpoation of America, (Dockets Nos. 5860 and 67 3).

This focusing action upon the generated cathode ray pencil is providedlfor byarranging a second anode member |51 upon the inner tube wall andapplying to the anode |51 (from a source of Voltage |59 orvdirectly fromthe socket power unit) a voltage of the order ofv four times thatapplied to the anode member l5'. The second anode member |51 extendsfrom the cone-shaped portion of the tube inwardly toward the neck of thetube in the form of a conducting coating so that between the inner endo'f the second anode |51and the anode |5| an electrostatic eld isproduced which tends to conne .the electrons forming the cathode raypencil to a sharply dene'd spot upon the uore'scent screen |55. At thesame time the higher voltage upon the sec'- ond anode |51 causes anacceleration of the electron stream after it has been deflected, for

synchronizing signal impulse fromrthe transmitter in accordance with thedisclosure set forth in the above mentioned application of R. D. Kell.

Similarly, the cathode ray pencil is caused to move in a verticaldirection, or in other words,

up and down across-the screen |55, looking at Fig. 4, by means of thevertical deecting coils IE5 which are connected with the verticalsynchronizing signal generating source |61 to which is supplied thevertical synchronizing or framing signal transmitted from the point oftransmission. The vertical synchronizing signal impulse serves tosynchronize or frame the received image signals in a manner which hasalso been described and claimed in the above mentioned application of R.D. Kell.

As image signals transmitted from the transmitter 95 within the timeperiod I, as shown by and no resulting light spot appears.

' the curve of` Fig. 1 are received so as to be conreproducing tube |45from the direction'shown by the arrow 'of Fig. 4 will observe lightspots hav'ingjaryingl intensities which correspond to the varyingintensities of light and shadow on .similarly coordinated elementalareas of the subject of Vwhich the image is to be produced.

The cathode ray tube |43 and the coordinated sound reproducer |31 may,where desired, be mounted within an appropriate cabinet, as has beendisclosed and claimed in-my previously )granted U. S. Patent #1,870,702,with which arrangement it is possible to view the reconstructed imagethroughoutl a wide angle by observing the image in the lid of thecabinet within which the television image reconstructing tube and thesound reproduoer are located.

. By portion (a) Fig. 5 I have shown aiportion of the fluorescent screen|55 and thereon have indicated by the solid lines M the paths traced byintensity controlled cathode rays, and by the dotted paths S theinterruption periodin the produced ray which occurs during theft returnline period. The synchronizing signalslwhich,

.as above stated, assume the characteristics of maximum black signals,ycause, when they influence or act upon the control grid |45 of the imagereconstructing tube |43, a complete absence or blocking of the cathoderay pencil so that the uorescent screen during the return line period isuninfiuenced by the `cathode ray By the portion (b) of Fig. 5 there isrepresented in conventional manner the wave form which may betransmitted throughout any one line scanning cycle. By this figure,portion I indicates the visual signals, whereas portion II indicates thesynchronizing and sound signals. l

In Fig. 6 there is shown in more detail the 1 storing arrangement of thesound signals in tubes 1 and III. From Fig. 6a, which may be consideredas constituting a view looking down on the top of the tube, it can beseen that the end portion of the tube is formed from a conducting plateI1 adjacent to which and immediately beneath which is an insulatingplate or strip of mica or equivalent I9. Immediately beneath the micalayer `is the plate member 2| forming the other plate of the condenserI5. The plate member 2| is divided into three distinct sections byappropriately. carbonizing separated areas 23 thereof. Thesecarbonizedareas are designated in Fig. 6b as the shaded areas 23 whereasthe non-carbonized areas 2| are unshaded. With this arrangement thedifferent sectionsv 2| and 23 have different properties so far as theemission of secondary electrons is concerned and, therefore, during thesweep path of the reversalof the cathode ray covers the various sectionsof the tube in the directions indicated by the arrows adjacent Fig. 6bdifferent intensity electrostatic charges produced upon the vvariouscondenser elements. may be utilized for transmission. Y

Having 'described my invention, what I claim is:

'1. The method of communicating intelligence which compriseselectrostatically storing a series of electrical energy representationsof the intelligence to be communicated during a.v

relatively long time period and scanning the stored electrical energycharges in inverse order to that of their production subsequent to theperiod of storing and during a relatively short period of time fortransmission, the periods of storing and transmitting being of the orderof at least six to one.

2. 'I'he method claimed in the preceding claim which includes, inaddition, the step of repeating the storing and transmission periods ata rate substantially equal to the rate ,of scanning each elemental stripof a subject for image transmission to reproduce the entire image at arepetition frequency at least equal to the frequency of persistence ofvision.

3. The method of transmitting intelligence which comprises producing aseries ofelectrostatic charges each of values proportional to producedintelligence signals and utilizing an electron beam to apply theelectrostatic charges to a transmission channel in inverse order to thatof their production andduring a time period substantially less than thetime period of their production. 4

4.v The method of communicating intelligence which comprises storing aseries of electrostatic representations of the intelligence to becommunicated and subsequently controlling an electron beam by theelectrostatic charges for transmitting' electrical ,energy modulated inaccordance with variations in the stored energy to utilization points ininverse order to that of its production. 1

5. The method of communicating intelligence whichffcomprises producing aseries of variable electro, tatic charges representative of a message tobe communicated during arelative long time period, and controlling anelectron beam by the electrotatic charges for transmitting signalsmodulated in proportion to variations in the stored electrical energyand in inverse order to that of the production of the stored energy sub-6. e method claimedin the preceding claimV which includes, in addition,the step of sequentially repeating the production of the electrostaticharges in an order inverse to that of the 7. The method of receivingtransmitted intelligence signals which comprises receiving during arelatively short time period a series of sound signals in inverse orderto that of generation,

producing an electric non-visible electrostaticv record of the receivedintelligence signals in the order of reception, and controlling acathode ray pencil to produce from the electrostatic sound record ininverse order to that of its production electrical signal energy, andthen converting the produced electrical signal energy into an audiblerecord of the sound originating at the point of transmission of thesignals.

8. In a system for transmitting intelligence, the method which comprisesproducing from a series of sound signals a series of electrostaticcharges proportional to differential portions of the entire series ofgenerated sound signals, controlling a cathode ray by the'electrostaticrsignals t apply the signals to a transmission channelin inverse order tothat of production and during a time period of the order of one-ninth ofthe v period during which the electrostatic signals were produced,receiving the signals applied to the transmission channel, producingfrom the received signals a series of electrostatic recordsrepresentative of the generated intelligence and in inverse order tothat of its production, controlling a cathode ray beam so as to produceelectrical signal energy representive ofv the received electrostaticrecords in inverse order to their production and at a rate of the orderof nine times slower than that of their production and translating theproduced energy into audible intelligence.

9. A system for receiving intelligence signals transmitted in reverseorder to that of production which comprises means for receiving during arelatively short time period a series of signals representative of theintelligence signals developed Within a relatively long time intervalbut in inverse order to that of the generation of the intelligencesignal, means for producing an electrostatic record of the receivedintelligence signals in the order of reception, and an electricalcommutating means for producing from the electrostatic intelligencesignals record in inverse order to that of its production and audiblerecord of the intelligence signals originating at the point oftransmission of the signals.

10. In a system for transmitting intelligence, a source of soundsignals, means for producing from the series of intelligence signals aseries of 4electrostatic charges of values proportional to the generatedintelligence signals, a transmission channel, electrically operatingdistributing means for applying the electrostatic charges to thetransmission channel to produce a series of signals representative ofthe electrostatic charges, said signals occurring in inverse order tothat of production of the charges and active during a time period atleast no greater than one-ninth of the period during which theelectrostatic charges were produced, means for receiving the signalsapplied to the transmission channel, means for producing from thereceived vsignals a series of electrostatic signal recordsrepresentative of the generated sound and in inverse order to that ofits production, and electrically operative distributing means forcausing the electrostatic record produced at the receiver' means tobecome audible in inverse order to its production'and at a rate at leastnine times slower than that of its produc- 11. 'I'he method oftransmitting and receiving' television image signals and relatedintelligence signals transmitted upon a single carrier frequency whichcomprises converting a series of light values from a subject intoproportional electric current values, generating a carrier current,modulating the generated carrier bythe produced electric currents,simultaneously converting in-Y telligence signals accompanying therepresentation of which the image is desired into a series ofproportional electrostatic charges, simultaneously interrupting theimage signal modulation of the carrier and modulating'the generatedcarrier byv the produced electrostatic signals in inverse order to thatof production during a time period of the order of one-ninth the periodof initial modulation by the image signals, repeating the sequence ofeach independent and separate modulation of the generated carrier at arate per second at least equal to the highest intelligence frequency tobe transmitted, receiving the modulated signals, producing from theimage modulated received signal a series of light intensitiesrepresentative of the various light values of the subject at the pointof transmission, interrupting the production oi light values at timeperiods corresponding to the time periods of interruption of the lightmodulation at the point of transmission, producing during the period oflight modulation interruption a series of electrostatic chargesrepresentative of sound in the order corresponding to the order oftransmission and of an intensity proportionate to the intelligencesignals at the point of transmission, repeating the production .ofvarying light values from received signals at a rate corresponding tothe repetition rate of transmission, and producing during eachrepetition of light values an audible indication of the intelligencesignals related to the next previously produced series of light valuesand for a time period identical to that required to produce eachseriesof light values.

12. The method of sequentially transmitting and simultaneouslyreproducing a plurality of independent intelligence signals which comtheproduced electrostatic signals in inverse order to that of productionduring a time period which is a fractional part only of the period ofmodulating the generated carrier by the produced electic current values,simultaneously converting the second of the signals into a series ofproportional electrostatic charges, simultaneously interrupting thecarrier modulation by the first signals and modulating the generatedcarrier by all of the produced electrostatic signals in inverse order tothat of production during a time period which is a fractional. part ofthe period of modulation by the rst series of signals, repeating thesequence of each independent and separate modulation vof the generatedcarrier at a rate per second at least equal to the repetition frequencyrate of persistence of vision, receiving the modulated signals,producing from one of the modlated received signals a series ofresponses representative of the rst series of signals originating at thepoint of transmission, interrupting the trostatic charges representativeof sound in the ordercorresponding to the order'of'transmission and ofan intensity proportional to the intelligence signals at the point oftransmission, repeating the production of varying light values fromvreceived signalsat a rate corresponding to the repetition rate oftransmission, and producing during each repetition of light values anaudible indication of the intelligence related to the next previouslyproduced series of light values and for a time period identical to thatrequired to produceeach series of light values.

13. A system for communicating intelligence between a plurality ofpoints which comprises means for electrically storing energyrepresentative of the intelligence to be communicatedl andcommutatingmeans for subsequently transmitting the stored electrical energy toutiliza-r tion points in inverse order to that of its production andprior-to the production of subseseries of electrical waves representing,in inverse order, the original intelligence subsequent to the periodofrstcring and means for repeating the operations continuously duringrelatively short periods of time of the order of the period ofpersistence of vision, the alternate periods of energy storing andre-conversion being of thel order of nine to'one.

15. In a system for transmitting sound energy, means for producing aseries of electrostatic charges of values individually proportionate toinstantaneously produced sound signals and a cathode ray device forneutralizing each of the electrostatic charges produced and therebyapplying a signal representative thereof to a transmission channel ininverse order to that of Atheir production and during a time period ofthe order of one-ninth that oi the period of their .production.

16. The system claimed in the preceding claim which includes, inaddition, means for 'sequentially repeating the alternate production ofthe electrostatic charges and the neutralization thereof at a repetitionrate per second of the order of 24.

17. A system for reconverting transmitted signais distributed duringshort time intervals into audible signals of apparent long durationwhich comprises means for receiving during continually interruptedrelatively short time periods a series kof signals representative ofintelligence eil'ects in inverse order to that of generation, means forproducing from the received signals an electrical non-visible record ofthe received signals in the same order of reproduction as the order ofreception, and cathode ray means for producing from the electricalrecord formed an audible record of an order of occurrence inverse tothat in which the electrical record is produced so as to represent theintelligence originating at the point of transmission of the signals.

l 18. In a system for transmitting intelligence signals, means forproducing from a series of andere sound originating at a source anelectrostatic record oi.' intensity proportionate to the generated soundsignals, a cathode ray for applying the f electrostatic signals to atransmission channel in inverse order to that of production and during atime period of the order of one-ninth the period during which theelectrostatic charges were produced, means for receiving the signalsapplied to the transmission channel, means for producing from thereceived signals a series of electrostatic recordings representative ofthe initially produced sound and in inverse order to that oi' theirproduction, and electrically operating' distributing means forconverting thesecond-named electrostatic record into a series of audiblesignals in inverse order to the production ci the electrostatic chargesand at a rate of the order of nine times slower than the rate ofproduction.

I9. 'Ihe system claimed in the preceding claim which includes, inaddition, means at the point charges, cathode ray means for causing thegen.

erated carrier to be modulated by all of -the produced yelectrostaticsignals in inverse order to that of the actual time of production, meansfor sequentially controlling the modulation so that the carrierfrequency modulation is controlled at any instant by one of the producedsignals only and the duration of each control period corresponds toperiods of picture scanning and interruption.

21. A receiving system for receiving signals transmitted in accordancewith claim which -comprises means for receiving modulatedy plctorial andintelligence signals, means for producing from the pictorially modulatedreceived signals a series of lighty intensities representative of thel'ght values at the point of transmission, means for interrupting theproduction ot light values of time periods corresponding -to the timeperiodsof interruption of the light modulation at the point oftransmission, a cathode ray device for producing during the period oflight modulation interruption a series of electrostatic chargesrepresentative of intelligence inthe order corresponding to the order oitransmission and of an intensity proportional to the intelligencesignals at the point of transmission, means ior causing a repetition ofthe production of varying light values and of stored intelligenceindications from received signals at a rate corresponding to therepetition rate of transmission,

VLADIMIR K. ZWORYKIN.

